The National Football League's share of playoff advertising revenue relative to its three main competitors—the National Basketball Association, Major League Baseball and the National Hockey League—increased to 62%, from 52%, over the past four years.

Explanation: Although regular-season television ratings dropped an average of 17% combined over 2016 and 2017, the NFL postseason (including the Super Bowl) remained the most dominant programming.

League postseason ad spending share.Forbes

The four-year period for the NFL and MLB encompassed the postseasons following the 2014 and 2017 seasons; for the NBA and the NHL, the 2013-14 and 2017-18 seasons.

During the same period, the NBA's share of postseason advertising revenue fell to 24%, from 32%; MLB's to 10%, from 11%; and the NHL's to 4%, from 5%, according to MediaRadar, an advertising intelligence and sales enablement platform.

MediaRadar's study found that advertisers spent more than $3 billion on TV ads across the four major leagues. More than 725 companies advertised during one or more of the different leagues’ playoffs. However, over 50% of the total ad spend came from just 23 companies, including General Motors, Anheuser-Busch Companies and AT&T.

Of those 23 companies, 19 of them advertised during all four of the leagues’ playoffs. Verizon came out on top as the highest-spending advertiser. The company was the only one to be named a top-10 spender across all four sports and took the No. 1 spot for both the NFL and MLB playoffs.

“When comparing advertising revenue between the 2017 and 2018 playoffs for these four major leagues, the NFL dominates,” Todd Krizelman, CEO of MediaRadar, wrote in a press release. “Despite the NFL’s public controversies during the 2017-2018 season, the league still saw a 90% renewal rate while the NHL, MLB and NBA all saw renewal rates between just 55% and 65%.”

Caveat: While the number of NFL playoff games are fixed each season, the number of playoff games in MLB, the NBA and the NHL can significantly fluctuate from season to season.

The NBA experienced a 9% decrease in the number of companies advertising during its playoffs. Despite that dip, the NBA still attracted the most advertisers and had over 100 more advertisers than the NFL. The NBA playoffs attracted more than 125 companies that did not advertise during any of the other leagues’ playoffs, including J.C. Penney, Goodyear Tire & Rubber, and Garmin.

My mentors were James Walker Michaels, Geoffrey N. Smith and William Baldwin. I started out in the statistics department of Forbes in the mid-'80s then transitioned to writing. I mainly wrote about high-priced stocks that I believed were doomed. Example: my story on CUC Int...